I've got a Saab 900 S Talladega Edition. I haven't done anything but add a Borla muffler. The hatchback is very practical for road trips but I'm thinking FWD was a mistake.
(not my car but very similar)
Nothing amazing. Though it's got the Talladega spoiler and air dam which set it apart from other NG900s and 9-3s, and best of all no monthly payments.
Next up will probably be a Volvo S60 R (300hp, AWD), or maybe even an Evo. Nowadays even factory NA engines can produce 100hp per liter of displacement (new Civic Si) so I'm thinking that the goal of any forced induction system should be 200hp/L, like one version of the Evo VIII sold in the UK.
Anyone into tuning will definitely dig this anime. There's an arcade game based around it too, Wangan Midnight Maximum Tune 3, which is just amazing if you can find a machine. There's an arcade in Toronto where Cantonese kids 4-way battle well past 4 a.m. every weekend.